Sudden decrease in organic search traffic - is Cumulative Layout Shift to blame?

I noticed a few weeks ago a huge drop in my organic search traffic (consistently -50% YOY). I'm trying to diagnose the cause and the only thing I can from from Google Search Console is 3,000+ mobile pages being identified as having "CLS issue: more than 0.25 (mobile)." I believe the culprit is a slow-loading Google ad banner that pushes everything down. I had added it to my site about a week before the traffic decrease. I've removed the ad unit and am waiting for Google to validate the fix. Would this be a potential cause of the sharp decrease?